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    Subject[PATCH 4.14 38/50] bonding: fix a potential double-unregister
    Date
    From: Cong Wang <xiyou.wangcong@gmail.com>

    [ Upstream commit 832707021666411d04795c564a4adea5d6b94f17 ]

    When we tear down a network namespace, we unregister all
    the netdevices within it. So we may queue a slave device
    and a bonding device together in the same unregister queue.

    If the only slave device is non-ethernet, it would
    automatically unregister the bonding device as well. Thus,
    we may end up unregistering the bonding device twice.

    Workaround this special case by checking reg_state.

    Fixes: 9b5e383c11b0 ("net: Introduce unregister_netdevice_many()")
    Reported-by: syzbot+af23e7f3e0a7e10c8b67@syzkaller.appspotmail.com
    Cc: Eric Dumazet <eric.dumazet@gmail.com>
    Cc: Andy Gospodarek <andy@greyhouse.net>
    Cc: Jay Vosburgh <j.vosburgh@gmail.com>
    Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/bonding/bond_main.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
    index 9ddbafdca3b05..a6d8d3b3c903d 100644
    --- a/drivers/net/bonding/bond_main.c
    +++ b/drivers/net/bonding/bond_main.c
    @@ -2010,7 +2010,8 @@ static int bond_release_and_destroy(struct net_device *bond_dev,
    int ret;

    ret = __bond_release_one(bond_dev, slave_dev, false, true);
    - if (ret == 0 && !bond_has_slaves(bond)) {
    + if (ret == 0 && !bond_has_slaves(bond) &&
    + bond_dev->reg_state != NETREG_UNREGISTERING) {
    bond_dev->priv_flags |= IFF_DISABLE_NETPOLL;
    netdev_info(bond_dev, "Destroying bond %s\n",
    bond_dev->name);
    --
    2.25.1


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